<?php

$id =90;

$str1 = "sdfs{$id}dfsd";

$str2 = 'sdfsdfsd$id';

$null=90;

var_dump($null);

// var_dump($str1,$str2);

// 定界符
$echo  =  <<<xbs
<script type="text/javascript">var screen_width = parseInt(window.screen.width); if(screen_width < 1200){ document.write('<div class="small-screen">'); }else{ document.write('<div class="wide-screen">'); }</script><header class="header"><div id="usrbar" class="userbar"><div class="my-info menu-hide"  onmouseover="this.className='my-info menu-show'"  onmouseout="this.className='my-info menu-hide'"><span><a href="http://www.baidu.com/p/%E5%AD%A6%E5%B9%B6%E6%80%9DPHP?from=jingyan" target="_blank" id="username" class="g-un" enable="false">学并思PHP<i class="i-arrow-down"></i></a></span><div class="dropdown-menu" ><a href="http://i.baidu.com/?from=jingyan" target="_blank" id="user-my-home" >我的主页</a><a href="http://passport.baidu.com/center" target="_blank" id="username" >帐号设置</a><a href="http://passport.baidu.com/?logout&aid=7&u=http://jingyan.baidu.com" id="usrbar-logout">退出</a></div></div>&nbsp;|&nbsp;<span><a id="my-home-exp" href="/user/nuc" target="_blank" log="type:100,pos:usrbar">我的经验</a></span>&nbsp;|&nbsp;<span><a id="my-income" href="/user/nuc/income" target="_blank">我的收入</a></span>&nbsp;|&nbsp;<span id="mnum"></span>&nbsp;|&nbsp;<span><a href="https://www.baidu.com/" target="_blank">百度首页</a>&nbsp;</span></div><div id="top-search-box" class="top-search-box"><div class="inner-warp"><div class="s-nav"><a class="logo" href="http://jingyan.baidu.com"><img src="//exp.bdstatic.com/static/common/widget/top-search-box/logo_1e63520.png" width="137" height="46" alt="百度经验" /></a><ul class="channel"><li><a href="http://news.baidu.com/" log="type:3100,menu:1" rel="nofollow">新闻</a></li><li><a href="http://www.baidu.com/"  log="type:3100,menu:2" rel="nofollow">网页</a></li><li><a href="http://tieba.baidu.com/" log="type:3100,menu:3" rel="nofollow">贴吧</a></li><li><a href="http://zhidao.baidu.com/" log="type:3100,menu:4">知道</a></li><li><strong>经验</strong></li><li><a href="http://music.baidu.com/" log="type:3100,menu:5" rel="nofollow">音乐</a></li><li><a href="http://image.baidu.com/" log="type:3100,menu:6" rel="nofollow">图片</a></li><li><a href="http://video.baidu.com/" log="type:3100,menu:7" rel="nofollow">视频</a></li><li><a href="http://map.baidu.com/" log="type:3100,menu:8" rel="nofollow">地图</a></li><li><a href="http://baike.baidu.com/" log="type:3100,menu:9" rel="nofollow">百科</a></li><li>
xbs;

var_dump($str);

?>
<!DOCTYPE html>
<html lang="en">
<head>
	<meta charset="UTF-8">
	<title>Document</title>
</head>
<body>
	<?php 

	$str = <<<xbs


xbs;	

	 ?>
</body>
</html>